The shuttleless or airjet weaving process has been widely adopted for weaving glass fabrics of improved quality and edge to edge uniformity. However, the resulting product has a feathered edge that is apt to become unravelled during further processing and treatment of the woven glass cloth. The need to secure the feathered edges of glass fabrics woven on a shuttleless loom is apparent. Several procedures have been used in the past to stabilize yarns at their crossover points. This may take the form of stabilization throughout the full width of the fabric for specific applications, such as tire cords, as illustrated in U.S. Pat. No. 3,695,326, or it may take the form of stabilizing only an edge of the fabric, as in U.S. Pat. No. 3,515,623. This latter patent describes securing the edge of a woven glass fiber fabric by weaving the fabric with a thermoplastic material such as nylon in strand form using the nylon yarn as selected warp ends. After weaving, the fabric is heated in the area of the woven nylon yarns. This heating locally melts the woven thermoplastic strand and serves to stabilize the fabric structure of the resulting product and to bond the warp and weft crossovers to provide security against ravelling. In the weave arrangement depicted in this patent, the thermoplastic strand material is woveninto the material in leno fashion.
The use of a leno woven thermoplastic strand to locally stabilize a fabric structure has a number of disadvantages--significant temperatures are required to locally melt the thermoplastic strand material and to cause the overlapping glass fiber strands to bond. Typically, this heating required for thermobonding is in the range of 350.degree.-500.degree. F., however such high temperatures often cause brown discoloration at least at the edges of the glass fabric due to charring of the warp size and yarn binder, two processing adjuvants commonly used in the weaving of fiberglass cloth. Moreover, thermoplastic strand materials of this type tend to melt unevenly causing unacceptable lumps in the resulting glass fabric and thermoplastic build-up on the elements used to melt the thermoplastic yarn. Most annoying are the noxious fumes given off by certain of the thermoplastic yarns, particularly nylon and vinyl, during the heating or thermobonding operation.
Other approaches to secure the edges of woven materials include the use of adhesive tapes attached to the ends of glass cloth, resin varnishes, or powdered hot melt resins as described in U.S. 4,428,995.
None of these prior procedures is well suited to prevent edge ravelling of a glass fabric woven on a commercial scale on a shuttleless loom to produce a secured, feathered edge fiberglass fabric.